STUDY TECHNIQUEOPTAN methods used by the

SAFOP

Study Team naturally follow on from SAFAN

techniques and SYSOP

examination sessions. (Chapters 4.0 and 5.0 of this EngineeringGuideline.)Detailed complexity of all Operator actions and decisions makes it unlikely that a

completeassessment of every eventuality will be achieved. However, by drawing

attention to certainsalient points and general problems, possibility of human error should be considerablyreduced.Anything which makes human operator’s work more difficult can lead to mistakes. Operatorsmay develop poor work habits to cope with difficulties. This may lead them to either forget todo something, or to use wrong working methods. These habits may be tolerated undernormal working conditions but are likely to give rise to serious problems when combined withpower plant failure or loss of supply.Major incidents usually occur through combination of minor failures. For example, one

item(such as a VDU display, which is difficult to read) may seem trivial when considered alone,but when considered with other factors (such as heavy workload) may have

seriousconsequences.To assist the team in its study, Operator tasks in both Control Room and Field are subdividedunder three main headings. These are:

•

Normal Operator Duties.

•

System Switching.

•

Abnormal or Emergency Conditions.Each of these duties are further subdivided under headings which attempt to establish acorrelation between procedures envisaged and situations considered. These headings,defined as key tasks, are:

•

Monitor/Check.

•

Make Decisions.

•

Actions.Typical questionnaires to establish main tasks for Control Room and Field Operators areprovided in APPENDICES 3 and 4.

SAFOP Guidelines

Doc. Ref.: QSP-FE-03-22August 2001 Page 39 6.3 STUDY PROCEDURE

This part of the study analyses an Operator's anticipated response to his task byassessing the ability of that Operator, his equipment and instructions to give optimumperformance with a minimum of error.The team should consider decisions Operators make in carrying out every step oftheir responsibilities, the information they need to identify and carry out their task, andthe relative frequency and level of demand on each of these

responsibilities.Operators must understand what is happening, have foreknowledge of requiredactions, and must know what results to expect from any actions taken.Like in SAFAN

and SYSOP

to assist the study team in its assessment, a list ofPrompt-words has been prepared. These are used to pose key questions. 'Have theOperators sufficient experience to perform their duties with a minimum risk of error?Suggested Prompt-words are:

•

Training.

•

Understanding.

•

Authority.

•

Instructions.

•

Information.These questions are applied in turn to specific Operator duties relating to variousitems of plant, equipment and procedures.Questions can also provide a framework for analysis of incidents in which humanerror is involved. Each question is intended; after consideration, to be answered by a'Yes' or a 'No' or by a qualified response 'it depends'. In an well-organised workingsituation the answers should all be 'Yes'.The study continues

until the team is satisfied that all relevant Operator tasks havebeen assessed and results recorded.

6.4 RECOMMENDATIONS

When the answer to the question is 'Yes' the likelihood of human error will probablybe low and changes to the situations to which the questions relate should not benecessary.A 'No' answer to the question reveals a potential for Operator error. To minimise riskof error, a specific operating procedure may need to be adopted or it may benecessary to incur additional expenditure on plant design modifications. However,such expenditure should be carefully evaluated against consequences.When the answer is 'it depends', then a Judgement must be made of whethercircumstances in which a problem arises, merit further attention.Questions applied and operator duties assessed, together with results obtained andrecommended actions, are recorded on 'OPTAN' Worksheets.Flowchart FIGURE 6-1 illustrates the study sequence for Operator Task Analysis.

SAFOP Guidelines

Doc. Ref.: QSP-FE-03-22August 2001 Page 40

6.5 EXAMPLES6.5.1 Control Room Operator Task Analysis

Selected Main Duty - Abnormal and emergency conditions.Selected Key Task - Take action.Plant Identified - Fault on 33 kV overhead line.Key Question Applied - Has he the AUTHORITY to switch out or attempt toreturn to service this item of plant?Answer Obtained - No.Action Recommended - Review limits of Authority and Responsibility.

Checksecurity of supply criteria.Record Results -

OPTAN Checksheet/Worksheet6.5.2 Field Operator Task Analysis

Selected Main Duty - System switching.Selected Key Task - Make decisions.Plant Identified - Major items of plant and equipment.Key Question Applied - Has he the UNDERSTANDING and TRAINING tocheck all relevant plant conditions on site beforeinitiating switching programs, e.g., Plant loading,Transformer Tap positions, etc?

Answer Obtained - No.Action Recommended - Review Training.- Define limits of Authority and Responsibility.

-

Review Electrical Operational Safety Proceduresand Electrical Safety Rules.Record Results -

OPTAN Checksheet/Worksheet

OPTANCHECKSHEET Promptwords

Plant Equipment Procedures

Monitor Generators Emerg.generatorMotors Transformer UPS

ThyristorControlsSwitching Isolating AuthorisationTraining ESRUnderstanding ESRAuthority ESRInstructions ESRInformation

SAFOP Guidelines

Doc. Ref.: QSP-FE-03-22August 2001 Page 41 Figure 6-1 - OPTAN STUDY SEQUENCE

START2. SELECT MAIN DUTY3. SELECT KEY TASK5. APPLY KEY

QUESTION6. OBTAIN ANSWERYES/NO/IT DEPENDS9. REPEAT STEPS 5 TO 8 FOR ALLKEY QUESTIONS7. RECOMMEND ACTIONS8. RECORD10. REPEAT STEPS 4 TO 9 FORALL ITEMS/ PLANT/ EQUIPMENT/PROCEDURES11. REPEAT STEPS 3 TO 10 FORALL KEY TASKS12. REPEAT STEPS 2 TO 11 FORALL MAIN

DUTIESFINISH4. IDENTY PLANT / EQUIPMENTPROCEDURES1. SELECT OPERATORCONTROL ROOM/ FIELD

SAFOP Guidelines

Doc. Ref.: QSP-FE-03-22August 2001 Page 42

OPERATOR TASK ANALYSIS (OPTAN) WORKSHEET

Project : Stage of Study (INITIAL/FINAL) :Location :Drawings :Sheet …….. of

……….Operator : CONTROL ROOM/ FIELD Operator Duty: NORMAL DUTIES/

SYSTEM SWITCHING/ EMERGENCY OPERATIONKey Task Plant/ Item Knowledge/ Resource YES/ NO Recommendation Action

SAFOP Guidelines

Doc. Ref.: QSP-FE-03-22August 2001 Page 44

APPENDIX 1 – NOTES OF GUIDANCE FOR SAFOP TEAM LEADERS